The Two Thread IDs of macOS: Measuring P/E Core Usage on Apple Silicon

Introduction Link to heading I needed a straightforward way to check programmatically how much time a process spends on P-cores vs E-cores. There&rsquo;s no high-level API for it, at least not that I know of – and yet this information matters whenever you care about consistent performance on Apple Silicon. I ran into this while working on Tango.rs , a benchmarking framework. When comparing two…